ES2686503T3 - Devices for the injection of gaseous streams into a bed of fluidized solids - Google Patents

Abstract

A gas distribution apparatus (90), comprising: a distribution manifold (93) in fluid communication with a gas supply source (94) and a plurality of injection nozzles (10); wherein each of the plurality of injection nozzles (10) comprises a tube (12) having a fluid inlet (24), a fluid outlet (26), and an axial length, wherein the fluid inlet (24) of at least one of the plurality of injection nozzles (10) is arranged within the distribution manifold (93), and in which the fluid inlet (24) comprises a plurality of flow restriction orifices (27 ) distributed axially through an input plate (28).

Description

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DESCRIPTION

Devices for the injection of gaseous streams into a bed of fluidized solids Background of the invention Field of the invention

The embodiments described herein generally refer to an apparatus for the injection of a gas stream into a bed of fluidized solids.

Background

In the refining and chemical treatment industries, as well as in other treatment industries, it is often necessary to inject a gas stream into a bed of finely divided solids, distributing the gas evenly across the entire cross-section of the bed. The gas injection has been designed to favor a uniform and intimate contact of the gaseous medium with the bed of solids, in order to achieve a purpose which is a chemical reaction between the gas and the solids and / or a mass transfer operation between Gas and solids.

An apparatus for the injection of gas into a fluidized bed usually consists of a flat grid plate provided with holes, a system of pipe grids, or a series of concentric rings. These distributors have been designed to physically cover the cross-section of the bed as much as possible in order to favor the uniform distribution of the gas throughout the length and width of the bed. The gas is introduced into the space below the flat plate distributor or inside the main head of a pipe grid and / or the ring distributor from a central supply source. From there, the gas flows through the entire pipe rack or ring system and is then discharged into the bed through a multiplicity of nozzles that distribute the gas evenly in the bed. Flat grid distributors are not, in general, completely flat, but have a slight plate shape up or down in order to better withstand the pressure exerted by the gas and / or the weight of the bed of solids located above. Flat grid distributors may or may not contain nozzles, but usually only use a hole configuration extended by the plate to allow gas to flow into the bed. Other embodiments of gas distributors for fluid beds of solids include distributors of the dome type and so-called "cap" distributors.

In order to achieve a uniform distribution of the gas medium, the injection nozzles have generally been designed with a cross-sectional area that will cause a pressure drop, or loss of load, as the gas flows to through the injection nozzles, from the distribution head to the bed of solids. Maintaining a positive pressure drop through the injection nozzles ensures that the gas flows uniformly to all injection nozzles despite the differences that may occur in the pressure in the bed at the time of discharge. Once the gas has flowed up through the bed of solids, the bed is "fluidized" and begins to behave like a liquid. Such a fluidized bed of solids will exert a pressure proportional to the depth of the bed and the density of the gas / solids mixture, in the same way as a liquid of similar density and depth would. Typically, such beds of fluidized solids will range in depth from a few meters (a few feet) to as much as 9 m (30 feet) or more and will exhibit a measured density ranging from a few g / cm3 (a few pounds per cubic foot) up to 5 g / cm3 (40 pounds per cubic foot). The resulting pressure exerted by the column of fluidized solids will range from as little as 6,985 Pa (1 pound per square inch (psi - "pound per square inch" -)) to as much as 68,946 Pa (10 psi) or more. Moreover, the bed of solids is often quite turbulent, which means that the pressure at any point in the bed fluctuates over time and will vary from one point to another at a given bed depth. For this reason, it is important to design the gas distributors with sufficient pressure drop, in order to overcome the expected pressure fluctuations at the location of the gas distributor in the bed. A typical "rule of thumb" for the design of gas distributors is that the minimum pressure drop should be 15% of the pressure drop in the bed for the injection nozzles pointing down, and 30% of the pressure drop in the bed for distributors pointed upwards.

In addition to maintaining a minimum pressure drop for a uniform distribution of the gas medium, the injection nozzles have also been designed to discharge the gas into the bed at a relatively high speed. If the gas velocity is too low, pressure pulsations may momentarily cause solids to be pushed back by pressure and flow from the bed into the injection nozzle. Such a return flow of solids into the injection nozzle is undesirable since it can lead to erosion in the injection nozzle due to the continuous abrasive action of the solids, and / or a plugging of an injection nozzle if the solids are housed. forming a solid mass. Moreover, if the solids are pressurized far enough into an injection nozzle, they can then enter the main head, where they are collected by the flowing gas to be discharged into one or more injection nozzles located further downstream. In the latter case, the result may be serious erosion in one or more injection nozzles located downstream with respect to the nozzle through which the solids have entered the header. For the purpose of

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avoid the return flow of solids into the injection nozzles, the speed in the nozzles is generally maintained above a certain minimum value, usually above approximately 6 m per second (20 feet per second ( fps - “feet per second” -)).

A problem that continues to plague gas distributors in fluid beds is the erosion of the injection nozzles at the time of discharge into the bed of solids. Over a prolonged period of time, the impact of solid particles on the discharge edge of the injector will cause gradual wear on the tip of the injector. As wear increases, the end of the nozzle can recede by erosion enough to destroy the place of attachment where the nozzle of the injector passes through the head. The result is a hole in the header and a loss of performance of the distributor. When this occurs, expensive and prolonged repairs are necessary to restore the performance of the grid or ring.

A procedure widely used in the petroleum refining industry, which makes use of beds of finely divided solids, is the fluid catalytic cracking (FCC) process. The FCC procedure is used for cracking heavy boiling diesel streams to obtain more valuable products of lighter boiling, such as gasoline and lighter hydrocarbons. The FCC process uses solid catalysts in powder form to facilitate the breakage of the carbon-carbon atomic bonds of the supplied diesel, in order to form smaller molecules that are within the boiling ranges of gasoline. In addition to the gasoline product, the process also results in substantial amounts of lighter gases, such as butane or propane, which are recovered and converted into valuable products. Catalytic fluid cracking is the "conversion" procedure most widely used in oil refining, and several million barrels per day of FCC capacity have been installed since the procedure was conceived in the early 1940s. Thus, Thus, the FCC procedure is of great economic value and is, in general, the unit of greatest use of an oil refinery in the United States as well as in most refineries around the world.

The catalyst used in the FCC process is a finely divided solid composed, for the most part, of silica and alumina, both crystalline and amorphous. The use of a powder catalyst has been the key feature that has contributed to the success of the FCC procedure and has led to the development of a whole area of procedural operations that has been called "fluidization." The finely divided powder catalyst can be behaved as a fluid when properly aerated or "fluidized" by means of air or other gas. The fluidized powder can be made to flow in lines or veins and will establish a certain level inside a container, as a liquid would. A fluidized powder will also generate a hydraulic pressure head proportional to the density and depth of the mixture contained in a container or in a vertical upright pipe, as a fluid would. Dust can also be pneumatically transported by a gas stream when the gas has sufficient speed. The ability to flow the powder catalyst between vessels has been tremendously beneficial in the development of a viable catalytic cracking process. The first attempts to use a fixed bed of catalyst pads were greatly affected by the need to regenerate the catalyst frequently in order to eliminate "coke" deposits that constitute a secondary product of cracking. Coke, mostly carbon, with some hydrogen and sulfur, deactivates the catalyst and has to be removed through a combustion stage. By making use of a "fluidifiable" catalyst, the catalyst can be continuously circulated between the reaction and regeneration vessels of an FCC unit, such that a cyclic process is not necessary to carry out the reaction steps. and regeneration.

In the FCC procedure, large volumes of air are used in the regenerator vessel to remove catalyst coke and restore catalyst activity. The air is usually injected into a bed of catalyst with coke content by means of distributors of the type of pipe grids or rings. The FCC process also makes use of large distributors of the type of pipes or rings in the pickling section, in which the spent catalyst contacts the steam to remove entrained hydrocarbons, before the catalyst is sent to the regenerator. Distributors of smaller pipes or rings are used elsewhere in the FCC procedure to inject steam or air in order to keep the catalyst powder in a "fluidized" or aerated state. The injection nozzles that are used in each of these areas of the FCC procedure may be subject to erosion, as described above.

Various attempts have been made to improve the design of the injection nozzles, in order to reduce the harmful effects of erosion and extend the life of the distributor. These include the use of exotic alloys and ceramic materials to make the injection nozzle itself harder and more resistant to erosion, protecting the discharge end of the injection nozzle with a hard surface finish, such as layers of metal coating or refractive layers, and / or changes in the design of the nozzle.

An air distributor design of the current state of the art for an FCC regenerator makes use of a pipe grid distributor and a two-stage injection nozzle design. Such a design has been shown in Figure 1A, which is a plan view of a pipe grid distributor consisting of three identical grids in a triangular arrangement, in order to cover the circular cross-section of an FCC regenerator. Figure 1B is an elevational view of one of the pipe grids, showing the way in which the supply artery

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Main air enters from the bottom, with three branches that also support the grid. All gratings are installed at the same height in the powder catalyst bed, so that they have, as approximate as possible, a uniform pressure with which the air is discharged. Figure 1C is a cross section of one of the arms of the grid, showing the arrangement of the nozzles, directed downwards at 45 degrees with respect to the vertical. This pipe grid design has proven to be very effective in physically distributing the air over the cross section of the catalyst bed, so that the burning of the coke is uniform.

Figure 1D is a sectional view of one of the air injection nozzles, which uses a two-stage tube, also referred to as a "Borda". Figures 1E-1H contains several views showing the nozzle arrangement within one of the grille arms. The metal grid arms are covered with an erosion resistant refractory material to protect both the grid arms themselves and the final length of the nozzles from erosion injection by the wear action of the catalyst particles.

The two-stage Borda tube or nozzle consists of a straight tube with a concentric hole at the inlet end. In the Borda tube design, the hole has been sized to provide a sufficient pressure drop to favor a uniform distribution of air through the grid, so that the pressure drop is usually between approximately 6,895 Pa and 20,684 Pa (between 1 and 3 psi). The orifice is followed by a larger diameter tubular section, which slows the gas in such a way that the discharge rate into the bed of solids does not cause excessive erosion and / or degradation of the catalyst. See, for example, the disclosure of Joseph W. Wilson: "Fluid Catalytic Cracking," p. 140-141, Penwell Publishing, 1997, which describes the use of a Borda tube as an injection nozzle in FCC applications.

The recommended length for the Borda tube is a minimum of six times the diameter of the tube, in order to allow the flow inside the tube to develop completely after the nozzle orifice. It has been established in practice that, if the nozzle is too short, the discharge flow will be turbulent and will result in excessive erosion at the tip of the nozzle.

While the design of the Borda tube and the use of hard materials for the construction of the nozzle and / or the protection of the tip of the nozzle have greatly improved the life of the grid distributors to service the FCC, these designs are still subject to excessive wear that requires periodic replacement, either individual nozzles of a grid arm, or of the entire grid arm. These types of repairs are difficult to carry out and can extend the time needed to perform routine maintenance during scheduled stop periods.

Another example of an air distributor that is used for the FCC catalytic regeneration process is disclosed in US Pat. No. 4,223,843. As disclosed herein, the air distributor includes a plurality of nozzles in a header ring and in a cylindrical housing, so that each nozzle has been formed with a divergent bore to eject high pressure air. The divergent bore of each of the nozzles has been formed with a half angle of less than 7 ° in order to provide a maximum air velocity without destroying the spent catalyst.

U.S. Pat. No. 4,460,130 discloses an injector nozzle arranged externally to the manifold, which has a central opening in an inlet, which extends from the nozzle to the central passage. The cross-sectional area of the central opening of the nozzle in the direction of flow is smaller, in at least one place, than that of the inlet, such that a major part of the pressure drop in the flowing gas from the central passage through the entrance and the nozzle, it is created by the nozzle. The central opening diverges outward at an angle of less than 15 °, in order to avoid the formation of a jet as well as the formation of stray currents.

The need for gas distribution devices that are subject to less erosive wear persists in the art.

Compendium of the invention

In one aspect, embodiments disclosed herein refer to a gas distribution apparatus as defined in claim 1. In some embodiments, the gas distribution apparatus described above may have been disposed within a container, such as to distribute a gas inside a container in order to carry out polymerization reactions, spent catalyst regeneration or coal gasification.

Further embodiments of the gas distribution apparatus are defined in the dependent claims.

Other aspects and advantages will be apparent from the following description and the accompanying claims.

Brief description of the drawings

Figures 1A (plan view) and 1B (elevation view) illustrate a distributor of pipe grids of the technique

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Figure 1C is a cross-sectional view of a grid arm of the prior art pipe grid distributor shown in Figure 1A, which includes an Injector tube injection nozzle.

Figure 1D is a detailed view of an inboard tube used in Figure 1C.

Figures 1E-1H present several perspective views of the arrangement of Borda tubes within the grid arm of Figure 1C.

Figure 2A (cross-sectional view) and Figure 2B (view from the injection that are not part of the present description.

Figure 3A (cross-sectional view) and Figure 3B (view from the injection according to the embodiments disclosed herein.

Figure 4A (cross-sectional view) and Figure 4B (view from the injection according to the embodiments disclosed herein.

Figure 5A (cross-sectional view) and Figure 5B (view from the injection according to the embodiments disclosed herein.

Figure 6A (cross-sectional view) and Figure 6B (view from the injection that are not part of the present description.

Figure 7A (cross-sectional view) and Figure 7B (view from the injection that are not part of the present description.

Figure 8A (cross-sectional view) and Figure 8B (view from the injection that are not part of the present description.

Figure 9A (cross-sectional view) and Figure 9B (view from the injection that are not part of the present description.

Figure 10 is a cross-sectional view of a pipe distributor grid arm that includes injection nozzles that are not part of the present description.

Figure 11 is a cross-sectional view of a pipe distributor grid arm that includes injection nozzles that are not part of the present description.

Figure 12 is a cross-sectional view of a container that includes a flat plate distributor that includes injection nozzles that are not part of the present description.

Figure 13 is a cross-sectional view of a container that includes a flat plate distributor that includes injection nozzles in accordance with the embodiments disclosed herein.

Figures 14A-14E show the internal flow configuration for a conventional Inboard tube injection nozzle, as developed by computational fluid dynamics analysis (CFD).

Figures 15A-15K show sequential frames of CFD animation of a conventional Inboard tube injection nozzle, illustrating the movement and instability of the jet coming from the hole and how instability is present along the entire path. to the end of the tube.

Figures 16A-20 show the internal flow configuration for modified Snorkels and Snorkels based on CFD analysis.

Figures 21, 22 and 25 show the internal flow configuration for injection nozzles, which are not part of the present description, based on the CFD analysis.

Figures 23 and 24 show the internal flow configuration for injection nozzles, in accordance with the embodiments disclosed herein, based on the CFD analysis.

Figures 26-31 compare the internal flow configuration for injection nozzles that are not part of the present description, based on CFD analysis, with that of conventional inboard tubes.

Detailed description

In one aspect, embodiments of this specification refer to an apparatus for the injection of a gas stream into a bed of fluidized solids. More specifically, embodiments disclosed herein.

inlet end) illustrate inlet end nozzles) illustrate inlet end nozzles) illustrate inlet end nozzles) illustrate inlet end nozzles) illustrate inlet end nozzles) illustrate inlet end nozzles) illustrate inlet nozzles input) illustrate nozzles of

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Memory refers to injection nozzles that can result in a certain gas velocity profile, in order to reduce or prevent erosion of the injection nozzle.

The injection nozzles may have a fluid inlet, in fluid communication with a gas distribution manifold, and a fluid outlet, in fluid communication with a container, for example. The fluid inlet of the injection nozzles according to the embodiments disclosed herein may include more fluid paths, parallel, perpendicular or transverse to the axis of the nozzle. The fluid paths may have been designed and distributed in the nozzle in a manner that results in one or more of: a pressure drop, or loss of load, desired through the nozzle; a stable gas velocity profile; a uniform velocity profile that may be centered with the nozzle outlet; and a maximum speed less than that which can cause degradation of the solid particles that are being fluidized.

Examples of injection nozzles according to embodiments disclosed herein have been illustrated in Figures 3-5, the examples in Figure 2 and 6-9 are not part of the present description. Although they have been illustrated in the characteristic figures of the injection nozzles as generally circular / cylindrical, other shapes / profiles can be used, such as square, rectangular, hexagonal, octagonal, etc. Thus, when reference is made to the diameter herein, it is understood that the diameter is an equivalent diameter for shapes other than the circular.

Referring now to Figures 2A (cross-sectional view) and 2B (view from the inlet end), an injection nozzle which is not part of the present description is illustrated. The injection nozzle 10 may include a tube 12 having a fluid inlet end 14 and a fluid outlet 16. The fluid inlet end 14 may be formed, for example, by a plurality of radial flow restriction holes 17, distributed circumferentially through the tube 12. As used herein, "plurality" refers to two or more, even if illustrated so as to present a different number. As shown in Figure 2B, the inlet end may be plugged by a back plate 18 lacking flow openings, such that only gas flow is allowed radially into the tube 12, through radial flow restriction holes 17.

The number and diameter of the radial flow restriction holes may depend on the desired pressure drop through the tube 12. The plurality of radial flow restriction holes 17 may be distributed through the tube 12 in a circumferential row. Other embodiments may include additional circumferential rows of radial flow restriction holes.

The ratio between an inner diameter Dt of the tube outlet and a diameter C of a radial flow restriction hole may be greater than 2: 1. In other embodiments, the ratio between an inner diameter Dt of the tube outlet and a diameter C of a radial flow restriction hole may be within the range between 2: 1 and 20: 1.

The plurality of radial flow restriction holes may have been disposed through the tube at a length L from an axial inlet end of the tube close to the inlet opening. In some embodiments, the length L may be less than 2 times the inside diameter of the fluid outlet 16; less than 1.5 times the inside diameter of the fluid outlet 16 in other embodiments; less than 1 time the inside diameter of the fluid outlet 16 in other embodiments; and less than 0.5 times the inside diameter of the fluid outlet 16, in still other embodiments. In other embodiments, the radial flow restriction holes may be located as close to the axial end as possible, in order to provide both manufacturing susceptibility and structural integrity.

Referring now to Figures 3A (profile view) and 3B (view from the inlet end), an injection nozzle is illustrated therein in accordance with the embodiments disclosed herein. The injection nozzle 10 may include the tube 12, which has a fluid inlet 24 and a fluid outlet 26. The fluid inlet 24 may be formed, for example, by a plurality of axial flow restriction holes 27, distributed axially through the input plate 28.

As shown in Figure 3B, the axial flow holes 26 may be distributed over the inlet plate 28 using a uniform separation. The use of a uniform separation can make manufacturing ease and structural integrity possible. More importantly, axial flow restriction holes with the same separation between them can make it possible to develop a centered and uniform flow profile.

By comparing Figure 3A and Figure 4A, in which the same numbers represent similar parts, the axial flow restriction holes 27 can have a length LO that can be adjusted to achieve a pressure drop or a profile of desired speeds. In some embodiments, the length LO may allow the flow within the axial flow restriction hole 27 to stabilize, thereby leaving the hole with a more uniform velocity profile, with the corresponding result of a more uniform velocity profile in fluid outlet 26. For example, the length Lo may be at least 4 times the diameter of an axial flow restriction hole in some embodiments; and at least 5 times the diameter of an orifice of an axial flow restriction orifice in still other embodiments.

The length from an outlet end 32 of a hole to the fluid outlet 26 should also be sufficient.

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to develop a uniform and stable speed profile. In some embodiments, the ratio between an axial length of the tube and an axial length of the plurality of flow restriction holes may be at least 4: 1; and be in the range between 5: 1 and 50: 1 in other embodiments.

The number and diameter of the axial flow restriction holes may also depend on the desired pressure drop through the tube 12. In some embodiments, a relationship between an inner diameter of the tube outlet and a diameter of a bore axial flow restriction is greater than 2: 1; and is in the range between 2: 1 and 20: 1 in other embodiments.

As illustrated in Figures 5A (profile view) and 5B (view from the inlet end), in which the same numbers represent similar parts, the axial flow restriction holes 27 may have gradually become narrowed. For example, axial flow holes 27 may increase in diameter from an inlet end 30 of the hole to an outlet end 32 of the hole, such that the outer diameter can gradually narrow at an angle a of up to about 15 ° in some embodiments; at an angle at between about 5 ° and 15 ° in other embodiments; and at an angle between 7.5 ° and 12.5 ° in still other embodiments.

Referring now to Figures 6A (profile view) and 6B (view from the inlet end), an injection nozzle is illustrated therein which is not part of the present description. The injection nozzle 60 may include a tube 62 having a fluid inlet 64 and a fluid outlet 66. The fluid inlet 64 may have been made, for example, as an annular orifice 68 surrounding a flow restriction device 70 As illustrated in Figure 6A, the flow restriction device 70 may include a disk 70D, properly suspended from the center of the inlet end of the tube 62.

The width W of the annular opening 68 may depend on the desired pressure drop through the nozzle 60, among other factors. In some embodiments, the diameter of the disk 70D may range between 0.5 and 0.95 times the inner diameter of the tube 62; and between 0.6 and 0.85 times the inner diameter of the tube 62 in other embodiments.

By comparing Figure 6A and Figure 7A, in which the same numbers represent similar parts, the flow restriction device 70 can have a length which can be adjusted to achieve a pressure drop or profile of desired speeds. In some embodiments, the length La may allow the flow to be stabilized within the annular orifice 68, whereby it exits the orifice with a more uniform velocity profile, with the corresponding result of a more uniform velocity profile at the fluid outlet. 66. For example, the length La may be at least 4 times the width W; and at least 5 times the width W in still other embodiments.

The length from an outlet end of the annular orifice to the fluid outlet 66 must also be sufficient to develop a uniform and stable velocity profile. In some embodiments, a ratio between an axial length Lt of the tube and a length of the annular flow orifice may be at least 4: 1; and be in the range between 5: 1 and 50: 1, in other embodiments.

As illustrated in Figures 8A (profile view), 8B (view from the input end), 9A (profile view) and 9B (view from the input end), in which the same numbers represent similar parts , the annular flow orifice 66 may be gradually narrowed, such as by the use of a flow restriction device 70C that can be conical. For example, the annular flow orifice 68 may increase in diameter from an inlet end of the orifice to an outlet end of the orifice, such that the outer diameter can gradually narrow at an angle p of up to about 15 ° in some embodiments. ; at an angle p between about 5 ° and 15 ° in other embodiments; and at an angle p between 7.5 ° and 12.5 ° in still other embodiments. As illustrated in Figure 9A, the outlet end of the conical flow restriction device 70C may be truncated (resulting in a frustoconical flow restriction device 70F).

Injection nozzles according to the embodiments disclosed herein, as described above, can make a stable velocity profile possible. Such injection nozzles may make possible a uniform velocity profile centered on the nozzle outlet. Injection nozzles according to the embodiments disclosed herein can prevent the generation of high velocity zones or localized jets that can cause particle degradation. Additionally, the injection nozzles disclosed herein can prevent the generation of areas that have a negative axial velocity near the nozzle outlet, resulting in a low erosion rate of the nozzle.

The injection nozzles described in the foregoing can be arranged in a gas distribution apparatus. The injection nozzles according to the embodiments disclosed herein can be used with any type of distribution apparatus in which a single gas phase is being distributed within a bed of fluidized solids. For example, a dome-type distributor and a cap distributor, among others. Such distributors can be disposed within containers intended to carry out various reactions or mass transfer between the gas and solids, including FCC catalytic regeneration vessels, gas phase polymerization vessels, coal gasification and iron ore reduction, among others.

Referring now to Figure 11, in which the same numbers represent similar parts, injection nozzles are illustrated in accordance with the embodiments disclosed herein arranged within

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of a gas distribution apparatus. Figure 10 shows injection nozzles that are not part of the present description, arranged in a gas distribution apparatus. The gas distribution apparatus 80 may include a ring type distributor (not shown) having a gas distribution manifold 82, in fluid communication with a gas supply source and a plurality of injection nozzles 84. Each one of the injection nozzles may include a fluid inlet 86, disposed inside the distribution manifold, and a fluid outlet 88. In some embodiments, such as that shown in Figure 10, the fluid outlet 88 may be located next to an outer circumference 89 of the gas distribution manifold 82. In other embodiments, as shown in Figure 11, the fluid outlet 88 terminates at a point external to the gas distribution manifold 82.

Similarly, referring next to Figures 12 and 13, in which the same numbers represent similar parts, injection nozzles are illustrated therein in accordance with the embodiments disclosed herein, arranged within a gas distribution apparatus . The gas distribution apparatus 90 may include a flat plate distributor 91 within a container 92, which has a gas distribution manifold 93 in fluid communication with a gas supply source 94 and a plurality of injection nozzles 95 Each of the injection nozzles may include a fluid inlet 96, disposed within the distribution manifold, and a fluid outlet 97. In some embodiments, such as that shown in Figure 12, the fluid outlet 97 may be located next to an upper surface 98 of the flat plate 99. In other embodiments, such as that shown in Figure 13, the fluid outlets 97 may terminate at a point above the upper surface 98 of the flat plate 99.

As mentioned above, the injection nozzles according to the embodiments disclosed herein can be used in gas distribution apparatus used for catalytic regeneration by FCC, for example. The injection nozzles according to the embodiments disclosed herein may additionally also be used in other parts of a cracking process, as illustrated in, and described with respect to, Figure 1 of the Patent of The USA. No. 5,314,610. As described in Patent 5,314,610, gas distribution apparatus can be used for the injection of a pickling medium, such as steam or nitrogen, into a catalytic cracking reaction vessel, or for the injection of oxygen or of air for combustion and removal of coke from a spent catalyst.

Examples

The following examples have been deduced by modeling techniques, and although the work was certainly carried out, the inventors do not present these examples in the past time to satisfy the applicable rules.

Simulations of injection nozzles in accordance with the embodiments disclosed herein have been compared with Embroidered and Embedded Tubes using the "computational fluid dynamics" (CFD). CFD is used to examine and compare flow patterns that result from a given injection nozzle configuration, as illustrated in Figures 14-17. As will be shown, injection nozzles according to the embodiments disclosed in the present invention can reduce the possibility of flow instabilities and the possibility of erosive wear at the tip of the nozzle. CFD studies were carried out using identical conditions for each simulated injection nozzle configuration, such that air flows and pressure drops were the same for each design.

Comparative Example 1

Referring to Figures 14A-14E, the results of CFD for an injection nozzle of the conventional Borda type which is widely used for gas distributors in fluidized beds are illustrated. The nozzle is 22.8 cm (9 inches) in length, has an inside diameter at the outlet of 3.8 cm (1.5 inches), and the inlet hole is 2.6 cm (1.04 inches) ) diameter. Figure 14A is a cross-sectional view of a gas distribution header, showing the flow velocity vectors within the header, the Overhead tube and the surrounding bed of solids. As expected, a high velocity jet is produced as the gas accelerates through the hole and diverges into the larger diameter of the Borda tube, downstream of the hole.

Figure 14B shows the velocity vectors in a single plane that cuts through a cross-section of the header and the Borda tube and exits outside, into a bed of solids. The plane has been oriented so that it is parallel to the direction of the general gas flow at the head. The CFD results indicate that the gas stream leaving the hole is influenced by the flow of gas into the header. Moreover, the animated CFD shows that the gas jet is not stable, but oscillates from one side to the other inside the Overboard tube.

Figures 14C and 14D are enlarged image captures of the gas stream coming from the hole, seen from two different directions, one of the views in the direction of the gas flow within the header, and the second view being perpendicular to the direction of the gas flow. It is clear from these views that the jet coming from the hole is influenced by the flow of gas in the header.

Figure 14E is a view along a single plane that passes through the center of the Borda tube, such that the orientation of the plane is perpendicular to the direction of gas flow within the header. It's amazing the

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finding that gas jet instability persists beyond the end of the nozzle and to the bed of the fluidized solids bed, even though the nozzle has the minimum recommended ratio between length and diameter (L / D) of 6, 0. Moreover, the instability of the gas jet actually results in a negative axial velocity in a part of the tube. The animated version of the CFD study shows that the region of negative velocity is not stable, but moves from one side to another inside the tube, as illustrated in Figure 15A, a view from one end of the entrance of the nozzle, and in Figures 15B-15K, containing sequential image captures (at equal time intervals) taken from the CFD analysis of an Injector tube injection nozzle, which show how the jet moves from one side to another inside the Borda tube. It is clear from these results that this nozzle design can allow solids to flow back into the region of the negative axial velocity, only to be collected and ejected at high speed when the gas stream changes sideways in the tube. The behavior of the unstable gas jet coincides with the wear configuration observed in these types of nozzles after use for a certain time.

Comparative Examples 2-5

Referring now to Figures 16-20 (Comparative Examples 1-5), image capture views are shown therein along an axial plane passing through various configurations of modified injection Board. All injection nozzles have been evaluated under the same inlet pressure conditions, with hole openings sized to provide a constant pressure drop of 14,479 Pa (2.1 psi) through the injector. Each nozzle has a length of 22.8 cm (9 inches) and has an inside diameter of 3.8 cm (1.5 inches) (L / D of 6).

Comparative Example 1 (repetition): Figure 16A is the conventional single-hole inboard tube, as shown previously in Figures 14 and 15 and shown here again as reference.

Comparative Example 2: In Figure 17, the Borda tube includes a double hole (each 0.6 cm (1/4 inch) in length and having a diameter of 2.6 cm (1.04 inches)) , with 1.9 m (0.75 inches) of space between the holes. The results of the CFD do not indicate any improvement in the stability of the jet or in the presence of regions of negative axial velocity in the nozzle tube, compared to a conventional inboard tube.

Comparative Example 3: In Figure 18, the hole includes a short sloping section at the downstream end. Again, CFD results do not indicate any improvement in jet stability or in the presence of regions of negative axial velocity in the nozzle tube.

Comparative Example 4: In Figures 19A (profile view) and 19B (view from one end of the nozzle inlet), the thickness of the hole is increased from 0.6 cm (1/4 inch) to 2.5 cm (1 inch) in length. This provision shows less instability in CFD results. However, the region of negative axial velocity is still present, although the position of the region of negative velocity is more stable.

Comparative Example 5: In Figures 20A (profile view) and 20B (view from one end of the nozzle inlet), the thick nozzle includes a long sloping region at the outlet end of the hole. This arrangement shows a very stable velocity profile. However, the gas jet is not centered in the tube and there is a relatively large, although stable, zone of negative axial velocity.

The CFD analyzes of an inboard tube and the modified inboard tubes of Figures 16A-16E exhibit an unstable flow and / or negative axial velocity, each of which is a characteristic of undesirable flow of an injection nozzle of gas.

Examples 1-5

Referring now to Figures 23 and 24 (Examples 3 and 4), image capture views along an axial plane through the injection nozzles used in apparatus according to the embodiments are illustrated. disclosed in this report. All injection nozzles have been evaluated under the same conditions as those in Comparative Examples 1-5 (the same inlet pressure, with hole openings sized to provide a constant pressure drop of 14,479 Pa (2.1 psi ) through the injector). Each nozzle is 22.8 cm (9 inches) long and has 3.8 cm (1.5 inches) inside diameter (L / D of 6).

Example 1: Figures 21A (profile view) and 21B (view from one end of the nozzle inlet) illustrate a CFD analysis of a hole similar to that illustrated in the embodiments described in relation to Figures 6A and 6B. Example 1 is not part of the present description. The hole configuration includes an annular opening that surrounds a flat disk (1.9 cm (0.75 inches) in diameter and 0.6 cm (1/4 inch) in length), suspended in the center of the entrance of the injection nozzle This nozzle has a very stable velocity profile. However, the velocity profile is not centered on the output. Additionally, there may be localized regions where a return flow could occur, and the nozzle may be difficult to manufacture.

Example 2: Figures 22A (profile view) and 22B (view from one end of the nozzle inlet) illustrate a CFD analysis of a hole similar to that illustrated in the described embodiment with respect to Figures 9A and

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9B. Example 2 is not part of the present description. The hole configuration includes a gradually narrowed cone, suspended at the inlet of the nozzle to form the opening of the annular hole. This nozzle behaves as well as that of Figures 21A and 21B from the point of view of stability, but shows an improvement as long as the velocity profile is almost perfectly centered on the nozzle tube. However, the nozzle can be difficult to manufacture.

Example 3: Figures 23A (profile view) and 23B (view from one end of the nozzle inlet) illustrate a CFD analysis of a hole similar to that illustrated in the described embodiment with respect to Figures 3A and 3B. The hole configuration includes seven (7) smaller holes to provide the same pressure drop as the single hole arrangement. This arrangement exhibits a fairly stable velocity profile, and the velocity profile at the nozzle outlet is very uniform. There are some areas of negative axial velocity, but these are confined to the inlet half of the nozzle and do not reach the tip of the nozzle.

Example 4: Figures 24A (profile view) and 24B (view from one end of the nozzle inlet) illustrate a CFD analysis of a hole similar to that illustrated in the embodiment described in relation to Figures 4A and 4B. The hole configuration includes a multi-hole arrangement (7 holes) similar to that of Example 3, except that the thin hole plate (0.6 cm (1/4 inch)) has been replaced by a thick plate ( 2.5 cm (1 inch)). The inclusion of the thick orifice plate improves the stability of the velocity profile, compared to Example 3, while also showing a very uniform velocity profile at the outlet of the injection nozzle. Moreover, the point at which the velocity profile becomes uniform occurs sooner than with the thin hole arrangement of Example 3.

Example 5: Figures 25A (profile view) and 25B (view from one end of the nozzle inlet) illustrate a CFD analysis of a hole similar to that illustrated in the embodiment described in relation to Figures 2A and 2B. Example 5 is not part of the present description. The hole configuration includes a multi-hole embodiment with eight (8) holes that have been moved to the side of the tube, instead of being placed on the back plate. There are no openings in the back plate. Again, the area of the holes has been sized to provide the same total pressure drop in the nozzle of 14,479 Pa (2.1 psi), as is maintained for all previous arrangements. CFD studies show that this arrangement results in a uniform and stable velocity profile. In the animated CFD result, almost no movement in the velocity profile has been detected. Moreover, the design of the nozzle is easy to manufacture with respect to the conventional inboard tube of Comparative Example 1.

Example 6: Figures 26-31 compare CFD analysis of a hole similar to that illustrated in Figures 2A and 2B, with a CFD analysis of the conventional inboard tube of Comparative Example 1 (illustrated in Figure 16 and repeated in Figures 27, 20 and 31 for convenience, so that 27A, 29A and 31A represent a profile view, and 27B, 29B and 31B represent a view from one end of the nozzle inlet). Hole configurations include multi-hole arrangements with eight (8) holes (Figures 26A (view from one end) and 26B (profile view of the nozzle inlet), six (6) holes (Figures 28A (view from one end) and 28B (profile view of the nozzle inlet)), and four (4) holes (Figures 30A (view from one end) and 30B (profile view of the nozzle inlet)), which have been moved to the side of the tube, instead of being placed in the back plate.There are no openings in the back plate.Once again, the area of the holes has been sized to provide the same total pressure drop in the nozzle of 14,479 Pa (2 , 1 psi), as maintained for all previous embodiments CFD studies show that these arrangements result in profiles of uniform and stable velocities (with reduced oscillation over time), as compared to the Borda tube conventional CFD studies also show that changing from eight (8) to six (6) and four (4) openings, the uniformity in the speed at the exit was improved.

As described above, the injection nozzles according to the embodiments disclosed herein may, advantageously, make possible one or more of a stable velocity profile, a uniform velocity at the outlet of the injection nozzle, and regions that have a limited negative flow rate. Advantageously, such injection nozzles can result in one or more of reduced erosion, reduced catalyst degradation and improved gas distribution.

While the disclosure includes a limited number of embodiments, those skilled in the art, with the benefit of this disclosure, will appreciate that other embodiments may be contemplated.

Claims (9)

5 10 fifteen twenty 25 1. A gas distribution apparatus (90), comprising: a distribution manifold (93) in fluid communication with a source of gas supply (94) and a plurality of injection nozzles (10); wherein each of the plurality of injection nozzles (10) comprises a tube (12) having a fluid inlet (24), a fluid outlet (26) and an axial length, wherein the fluid inlet (24) of at least one of the plurality of injection nozzles (10) is disposed within the distribution manifold (93), and wherein the fluid inlet (24) comprises a plurality of flow restriction holes (27) axially distributed through an inlet plate (28). 2. The apparatus of claim 1, wherein the fluid outlet (26) is close to an outer circumference of the distribution manifold (93). 3. The apparatus of claim 1, wherein the fluid outlet (26) is external to an outer circumference of the distribution manifold (93). 4. The apparatus of claim 1, wherein a ratio of an inner diameter of the fluid outlet (26) to a diameter of at least one of the flow restriction holes (27) is greater than 2: 1. 5. The apparatus of claim 1, wherein the axial length of the tube (12) is at least 5 times the internal diameter of the fluid outlet (26). 6. The apparatus of claim 1, wherein the plurality of flow restriction holes (27) are axially aligned with the tube (12). 7. The apparatus of claim 1, wherein a ratio of an axial length of the tube (12) to an axial length of at least one of the plurality of flow restriction holes (27) is at least 4: 1. 8. A container comprising the apparatus of claim 1 disposed within the container. 9. The container of claim 8, wherein the container is selected from the group consisting of a spent catalyst regenerator, a polymerization and gasification reaction vessel of carbon.